1. Field of the Invention
The present invention relates to a device for preventing or suppressing an electrical pre-arcing condition in a heated respiratory breathing circuit.
2. Description of the Related Art
Ventilator circuits are designed for directing breathing gas supplied by a ventilator or respirator to a patient. Typically, the breathing gas is humidified by a humidifier cooperating with the respiratory circuit, often located at or near the ventilator or respirator whereby the humidified gas travels along a substantial length of the inspiratory limb of the respiratory circuit. The humidified gas becomes cooled as it travels along the inspiratory tubing resulting in condensation or “rain out” inside the tubing. To prevent such condensation, which otherwise could interfere with the efficiency of the breathing circuit and possible injury to a patient, the circuit may be provided with heater wire extending along the interior of the tubing, or embedded in or otherwise secured along the wall of the tubing. Examples of such heated ventilator circuits are described in U.S. Pat. Nos. 4,682,010, 5,537,996, 5,640,951, and international application number WO 86/02566. A single heater wire loop having two ends attached to a plug or connector for supplying electrical current for heating the wire is commonly used.
In respiratory circuits, the breathing air supplied by the ventilator comprises a air mixture having a relatively high concentration of oxygen. It will be understood that because of such high oxygen levels, the gaseous mixture is extremely combustible. Because the heater wire is a resistive wire through which an electrical current passes to accomplish the heating, arcing caused by a short or an open circuit condition may result in ignition and subsequent combustion of the gaseous mixture and possibly causing extremely dangerous fires and injury to a patient.